Heat exchanger with fluid expansion in header

Abstract

A heat exchanger includes a first header and a second header and a plurality of heat exchange tubes extending therebetween. Each heat exchange tube has an inlet end opening to one of the headers and an outlet opening to the other header. Each heat exchange tube has a plurality of channels extending longitudinally in parallel relationship from its inlet end to its outlet end, each channel defining a discrete refrigerant flow path. The inlet end of each of the plurality of heat exchange tubes is positioned with the inlet opening to the channels disposed in spaced relationship with and facing an opposite inside surface of the header thereby defining a relatively narrow gap between the inlet opening to the channels and the facing opposite inside surface of the header. The gap may function either as a primary expansion device or as a secondary expansion device.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]Reference is made to and this application claims priority from and the benefit of U.S. Provisional Application Ser. No. 60 / 649,422, filed Feb. 2, 2005, and entitled MINI-CHANNEL HEAT EXCHANGER WITH FLUID EXPANSION IN A GAP BETWEEN THE TUBE AND THE HEADER, which application is incorporated herein in its entirety by referenceFIELD OF THE INVENTION[0002]This invention relates generally to refrigerant vapor compression system heat exchangers having a plurality of parallel tubes extending between a first header and a second header and, more particularly, to providing expansion of refrigerant within the inlet header for improving distribution of two-phase refrigerant flow through the parallel tubes of the heat exchanger.BACKGROUND OF THE INVENTION[0003]Refrigerant vapor compression systems are well known in the art. Air conditioners and heat pumps employing refrigerant vapor compression cycles are commonly used for cooling or cooling / heating air...

AI Technical Summary

Benefits of technology

[0012]It is a general object of the invention to reduce maldistribution of refrigerant flow in a refrigerant vapor compression system heat exchanger having a plurality of multi-channel tubes extending between a first header and a second header.

Problems solved by technology

Non-uniform distribution, also referred to as maldistribution, of two-phase refrigerant flow is a common problem in parallel tube heat exchangers which adversely impacts heat exchanger efficiency.

Two-phase maldistribution problems are often caused by the difference in density of the vapor phase refrigerant and the liquid phase refrigerant present in the inlet header due to the expansion of the refrigerant as it traversed the upstream expansion device.

Obtaining uniform refrigerant flow distribution amongst the relatively large number of small flow area refrigerant flow paths is even more difficult than it is in conventional round tube heat exchangers and can significantly reduce heat exchanger efficiency as well as cause serious reliability problems due to compressor flooding.

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